Experimental investigation on the dynamic flow behaviour and structure-property correlation of dual-phase high carbon steel at elevated temperatures

Abstract The rate and temperature-dependent deformation mechanism of high carbon steel (HCS) are of fundamental significance due to their comprehensive application in the mining industries. The influences of high strain rate under the influence of thermal loading on the deformation behaviour of HCS under compressive loading are investigated in this paper. Dynamic compressive tests at two different strain rates (750/s and 1750/s), as well as three different temperatures of 25 °C, 100 °C and 175 °C, were performed using a Split Hopkinson Pressure Bar (SHPB) testing machine and the corresponding changes in the microstructures were observed. The material exhibited four stages in the strain hardening rate behaviour during the deformation process along with an irregular trend in the ultimate strength and total elongation. X-Ray diffraction (XRD) peaks at ambient condition exhibited martensitic transformation, whereas, this transformation was suppressed with increasing strain rate. At elevated temperatures, the transformation of martensite into ferrite/tempered martensite (TM) and carbide precipitates was noticed. Moreover, the fractographic study of the deformed specimens provided an insight into the change in the distribution of the dimples which were mainly caused due to the different deformation activities. Transmission electron microscopy (TEM) results confirmed the formation of adiabatic shear bands for all the loading histories. Increase in the width of the shear bands was recorded with increasing strain rates whereas, concerning the influence of temperature, an overall decrease in the width was noticed. Substantial effect of the formation of carbide precipitates on the mechanical behaviour of the material was noticed during the high-temperature deformation process.